Our world is wearily accustomed to terrorist atrocities but, even so, a suicide bomber at a concert attended by thousands of teenagers breaks new and terrible ground, and will strike particular fear into the hearts of parents.
How can we ever hope to keep our children safe from harm if something as innocently joyful as a pop concert suddenly becomes a target for evil-doers?
Looking at the smartphone footage and listening to the eye witness accounts and reading all the tweets from desperate friends and families frantically searching for loved ones through the night, it will have been hard for many parents not to think to themselves: “What if that was me?”
What if the attack had happened last weekend when Ariana Grande was in Dublin?
Until late last night, the only reason I had for knowing anything about Grande was my two little girls. My littlest, in particular is a big fan of the singer, at least on those days when Taylor Swift or Katy Perry aren't her favourite. She is always asking me to play Grande songs in the car or on my phone.
Fret
I almost always do and she sings along with gusto as I quietly fret over the vaguely inappropriate and grown-up nature of some of the lyrics. Because fretting is – sometimes – what parents are best at.
Like most parents of young children, I go to great – and sometimes ridiculous – lengths to shield my children from bad news.
My desire to protect them frequently has me vaulting over toys, clothes and furniture scattered across my living room so I can turn Morning Ireland off when presenters start talking about something I think they might find upsetting.
If the content involves children coming to harm I run to the radio.
But I won’t be able to protect them from this news because this is a direct attack on their world and it will be the only topic of conversation among their classmates during big and little break at school today.
And when they come home from school this evening I will have to talk to them about what happened last night and explain that while what it was terrible, it will not happen to them because I will be able to keep them safe.
But I don’t know if that is true.
Several weeks ago we all went to Paris. In the days leading up to the trip, my children grew increasingly excited as they talked of all the things they wanted to see and do. They looked at pictures of the Eiffel Tower and compared it in size to the Spire and they planned their Mona Lisa selfies.
With each passing day they grew more excited and I grew more edgy. I played out various appalling scenarios in my head, all of which were informed by the terrorist attacks in Paris, Nice, Brussels and elsewhere.
I thought of ways I could keep them safe if the worst things happened. In my imagination I almost always came up short.
Fooled myself
And then after we arrived and as we stood in line for the Eiffel Tower and the Arc de Triomphe and the Louvre I kept watching for something. In Metro carriages I eyed fellow passengers suspiciously looking for signs of something, anything, suspicious.
But I had no idea what that something was. A man with a gun? An erratic driver? A suicide bomber?
I fooled myself into thinking that my watchfulness would keep my children safe but an incident like the one that happened last night just outside the Manchester Arena highlights just how ridiculous that notion is.
Parents can be as watchful as they like and they can do all they can to protect their children, but then someone walks up to the door of a concert as it is coming to an end and detonates a bomb.
Many of the children at the concert would have been there with their friends and without their parents. For some it would have been their first big night out alone.
At the best of times, such events are chaotic which makes the chaos following the attack almost beyond comprehension. It makes it all the more terrifying.
I know that we have to go about our lives as normal and to do otherwise is to let terror win. But such knowledge is well and good, until our children are deliberately targeted.
It is harder to stand defiant then.